Recurrent Acute Otitis Media and Tonsillitis due to Viral Upper Respiratory Infections: This is the most likely diagnosis given the frequency of otitis media episodes and respiratory infections, which are common in young children due to their immature immune systems and exposure to pathogens, especially with enlarged tonsils that may be contributing to the frequency of infections.

Allergic Rhinitis: Could be contributing to the frequency of respiratory infections by causing chronic nasal congestion and increasing the risk of secondary bacterial infections.
Enlarged Tonsils with Obstructive Sleep Apnea: While not directly causing infections, obstructive sleep apnea can lead to poor sleep quality, which might impair immune function and increase susceptibility to infections.
Immunoglobulin A (IgA) Deficiency: A common primary immunodeficiency that can present with recurrent infections, particularly of the respiratory tract.

HIV Infection: Although less common, HIV infection can cause recurrent and severe infections due to immunocompromise. Early diagnosis is crucial for management and prognosis.
Primary Immunodeficiencies (e.g., SCID, Chronic Granulomatous Disease): These conditions can lead to severe, recurrent infections. Identifying them early is critical for appropriate management, including possible bone marrow transplantation.
Anatomical Abnormalities (e.g., Choanal Atresia, Tracheoesophageal Fistula): Certain anatomical issues can predispose to recurrent infections and require surgical correction.

Cystic Fibrosis: While more commonly associated with gastrointestinal and pulmonary symptoms, cystic fibrosis can also lead to recurrent respiratory infections.
Chronic Granulomatous Disease: A rare primary immunodeficiency characterized by the inability of phagocytic cells to kill certain bacteria and fungi, leading to recurrent life-threatening infections.
Hyper-IgE Syndrome (Job Syndrome): Characterized by recurrent cutaneous and pulmonary infections and extremely high levels of IgE.